I have a 2003 A6 2.7 with 100K on it.
I'm getting a CEL that my independent mechanic says is a temperature sensor. He replaced the one in the lower hose, and the light went away. Now the CEL is back on, and I'm wondering if there is more than one temp sensor on the car.
The car runs great, and the temp guage remains normal where it always is.
Can anyone help?

Thanks

 

You need to scan to get the error code to be sure that it is the temperature sensor.

 

He did scan it and receiced the code for a temp sensor. He replaced the one in the lower hose. After some research I believe there are 2 more sensors on the car. Does anyone have a part number for the one on the back of the engine? Is it the green one from ECS?

 

That's the one, You will need an o-ring and the plastic clip that holds it in because it will break on you. (It will only break if you don't have another one on hand-you know how that works) It's tight back there lube the new o-ring with a thin coat of Vaseline and it will slide right in.

It is located on the right side, Driver European/Passenger U.S. against the fire wall. There is another sensor on the other side of the pipe and that is for the Aux water pump-not connected to your problem so don't bother that one.

you can see it here on my 3.0, I break every wire terminal I touch (That's why I used a cable tie). Try to squeeze push down and pull back to unplug it and put some dielectric grease in the contacts to keep them from oxidizing.

 

That's what it was. It took about 10 min to replace it.